It was proposed to use curable silicone compositions that form heat-resistant and light-proof cured products as coating or sealing agents (see Japanese Unexamined Patent Application Publications (hereinafter referred to as “Kokai”) Hei 11-1619, 2002-265787, and 2004-186168). However, although such curable silicone compositions demonstrate better resistance to heat and ultraviolet radiation than epoxy resins, they are inferior to epoxy resins in flexibility. Therefore, the use of these curable silicone compositions is associated with some problems such as damage of sealed elements and impaired adhesion to substrates.
On the other hand, known in the art are curable silicone rubber compositions that possess flexibility. However, these compositions have low strength and an insufficient modulus of elasticity.
Based on the results of a profound study conducted by the inventors herein, it was found that a curable silicone composition having a main component in the form of an organopolysiloxane with a previously introduced diorganopolysiloxane residue having a three-dimensional structure is capable of forming cured products of high hardness and improved resistance to cracking.
It is an object of the invention to solve the problems of the prior art by providing a novel organopolysiloxane, a method of manufacturing thereof, a curable silicone composition having the aforementioned organopolysiloxane as the main component and capable of forming a cured product of high flexibility, and a cured product obtained from the aforementioned composition.